Der Zerfall des Xe123,T 1/2=2,08h

Xe¹²³ (T _1/2=2.08 h) was produced by bombarding Te¹²² with 48 MeV α-particles. The radioactive Xe¹²³ gas was collected during irradiation in liquid air cooled glass ampoules. The gamma rays associated with the decay of Xe¹²³ have been investigated using Ge(Li)- and NaJ(Tl)-counters and a Ge(Li)-NaJ(Tl)-coincidence circuit. 57 gamma transitions in the energy range from 148.7 keV to 2559.1 keV have been found. By depositing the radioactive Xe-ions on Ti-foils sources were obtained thin enough to study the conversion electrons using a Si(Li)-counter. The conversion coefficients for the intensive J¹²³ transitions with low energy were determined. A level scheme for Xe¹²³→J¹²³ which accounts for almost all observed γ-transitions having 16 levels is proposed. Furthermore some new data for the J¹²¹ and J¹²³ decay are presented.     

A Si(Li) detector system for conversion coefficient measurements and application to the decays of51Cr and87Y

An electron detector system with a 3 mm × 100 mm² Si(Li) detector with a cooled FET and vacuum air lock for changing sources was constructed. The absolute efficiency was measured as a function of energy for use in the measurement ofK conversion coefficients. With the Si(Li) and a Ge(Li) detector, theK conversion coefficient of the 320 keV transition in⁵¹V was measured to be 0.00156 ± 0.00008 where theK conversion coefficients of the 661 and 279 keV transitions in¹³⁷Ba and²⁰³Tl were used as standards. From absolute detection efficiency measurements, theK conversion coefficients of the 388 and 483 keV transitions in⁸⁷Sr were measured to be 0.16 ± 0.02 and 0.0024 ± 0.0003, respectively.     

K conversion coefficients of transitions in87Sr

TheK conversion coefficients of the 388 and 483 keV transitions in⁸⁷Sr populated in the decay of⁸⁷Y have been measured with Ge(Li) and Si(Li) detectors by the NPG method. We find α _K values of 0.162 ± 0.010 and 0.00260 ± 0.00013 for the 388 and 483 keV transitions, respectively.     

A high-resolution spectroscopic study of the gamma radiation from the decay of96Nb

The decay of 24h⁹⁶Nb has been studied with a Ge(Li) spectrometer and with a Ge(Li)-NaI(Tl) coincidence spectrometer. A total of 27 gamma-ray transitions were observed, their energies and intensities measured. All but one of these have been incorporated into the level scheme of⁹⁶Mo. The level at 1,625.9 keV reported recently in (n _th, γ) work on⁹⁵Nb has also been observed through the decay of⁹⁶Nb. No experimental evidence has been found for previously proposed levels at 2,657 and 2,791 keV in⁹⁶Mo.     

Levels and transitions in125Te

Gamma transitions and levels of¹²⁵Te following the decay of¹²⁵Sb have been studied using Ge(Li) detector and NaI(Tl)-NaI(Tl) sum-coincidence spectrometer incorporated with a fast-slow coincidence circuit. In all, twenty five gamma rays have been reported, out of which two weak gamma rays with energies 366·0 and 402·0 keV have been observed and confirmed for the first time. These gamma rays have been fitted by assigning a new level of 402 keV energy. An ambiguous transition of energy 122·1 keV has also been confirmed. No evidence was found for the existence of 145·9, 315·0, 489·8, and 497·4 keV transitions. The accurate intensities for various transitions have been determined.     

Energy levels of174Yb populated in the decay of174Tm

The decay of the¹⁷⁴Tm activity has been studied with Ge(Li) detectors and with a Ge(Li)—NaI(Tl) coincidence arrangement. Gamma ray energies and relative intensities were determined. Five new gamma transitions are reported, four of which have been placed in the decay scheme in addition to the previously observed but unplaced 1305 keV transition. Five energy levels at 1557.7, 1762.1, 1781.1, 1877.5 and 2050.1 keV not earlier reported to be populated in the decay of¹⁷⁴Tm are suggested. Some spin and parity assignments are proposed and the intrinsic structure of several states is discussed in terms of two quasi-particle excitations. For the half-life of¹⁷⁴Tm a value 5.4±0.1 min was measured.     

The electron capture decay of 131Ba

The decay of ¹³¹Ba has been investigated by means of a 4π internal source scintillation spectrometer and a Ge(Li) detector. The L/K. and M/L electron capture ratios of the allowed transitions to the 373, 620 and 1048 keV levels in ¹³¹Cs have been measured. From these electron capture ratios, the ifQ_EC value and the exchange and overlap corrections X^L/K and X^M/L have been derived.     

Low-lying 134Cs excited states from the (n, γ) reaction

Low-energy γ-ray and conversion electron spectra from the ¹³³Cs(n,γ)¹³⁴Cs reaction have been investigated with a bent cyrstal spectrometer, β-speetrometer, Ge(Li) and Si(Li) detectors. Gamma-gamma coincidence measurements were made with the Ge(Li)-Ge(Li) arrangement. Gamma-gamma delayed coincidences have been studied with the use of the Ge(Li)-NaI(Tl) coincidence set-up. The decay of 2.9 h ^134mCs has been investigated with the prism β-spectrometer and Ge(Li) detector. The half-lives of the 176.403 and 257.112 keV levels have been measured to be 49.7 ± 0.8ns and 12.3 ± 1.1 ns respectively. The neutron binding energy B_n have been calculated to be 6891.4 ± 1.3 keV. Spin and parity assignments have been made for almost all the levels. The possible structure of the levels deduced is discussed.     

Gamma-ray spectra and positive parity bands in 158Gd

A Ge(Li)-NaI(Tl) pair spectrometer and a Ge(Li)-NaI(Tl) anti-Compton spectrometer were used to measure γ-rays from the reaction ¹⁵⁷Gd(n, γ)¹⁵⁸Gd. A detailed decay scheme for levels of ¹⁵⁸Gd was constructed up to an excitation energy of 2504 keV. Branching ratios for transitions from members of the positive parity bands to members of the ground state band were determined. It is shown that a single band-mixing parameter is not sufficient to explain the experimental results, and that even a four-band-mixing calculation does not provide satisfactory agreement. The binding energy of the last neutron is determined to be 7937.4±0.7 keV.     

Der Zerfall des Zn63

The decay of the 38.4 min-Zn⁶³ has been investigated using Ge(Li)-counters and a Ge(Li)-NaJ(Tl)-coincidence circuit. 43γ-transitions in the energy range from 364.5 keV to 3100.9 keV have been found and their relative intensities have been determined. A level scheme for Zn⁶³→Cu⁶³ having 24 levels is proposed. This accounts for all observedγ-transitions except one.     

The levels of144Pr from the decay of144Ce

The level scheme of¹⁴⁴Pr has been studied from the decay of¹⁴⁴Ce. The intensities and energies of gamma rays have been determined with a X-ray Ge(Li) detector. TheK-shell internal conversion coefficients for γ-rays have been measured with theK X-ray/γ-ray ratio method using NaI(Tl)—X-ray Ge(Li) coincidence techniques.     

Levels in208Pb populated in the decay of208Tl(ThC″)

Gamma rays in the disintegration of²⁰⁸Tl(ThC″) have been studied with Ge(Li)-Na I(Tl) anti-Compton and coincidence spectrometers. Several new transitions are reported most of which are placed in a decay scheme incorporating excited states in²⁰⁸Pb at 2,614.5, 3,197.6, 3,475.0, 3,708.3, 3,919.8, 3,960.9, 3,998.5, 4,125.3, 4,180.4, 4,296.1 and 4,480.0 keV. According to the present data, the recently reported intensity of 4.5±1.5% of beta groups feeding levels near 4.3 MeV is far too large.     

Coincidence measurements on the decay of Tm (87 d)

The decay of ¹⁶⁸Tm(87 d) has been studied with Ge(Li) detectors in singles and in coincidence with a NaI detector. The energies and intensities of the following previously established transitions were obtained: 79.8, 99.3, 173.8, 184.4, 198.3, 273.0, 348.5, 4.22.2, 447.6, 546.8, 557.0, 631.7, 645.75, 673.7, 720.4, 730.7, 741.4, 748.25, 816.0, 821.1, 829.9, 914.8, 928.9, 1014.2, 1167.3, 1277.3, 1323.7, 1351.4 and 1461.5 keV. Additional γ-ray transitions at 284.5, 853.2, 1262.6 and 1489.7 keV were observed. These data were combined with the available internal conversion electron data to obtain internal conversion coefficients. Branching ratios for E2 transitions de-exciting levels in the gamma band and E1 transitions de-exciting the negative-parity states were calculated and compared with theoretical estimates. Prompt and delayed coincidence measurements were carried out using a 2 mm Ge(Li) detector and a 7.6 cm × 7.6 cm NaI detector. Gates were set at 79.8, 99.3, 184.4, 198.3 and 447.6 keV and on transitions in the region from 700 to 850 keV. The delayed coincidence measurements were made to investigate the population and decay of the 0.12 μsec state at 1094.1 keV and support the placement of the 348.5 keV transition in the decay scheme. A revised decay scheme is presented.     

Beta decay of 28P

The β⁺ decay of ²⁸P has been studied with a Ge(Li)-NaI(Tl) escape-suppression spectrometer. The number of ²⁸Si γ-transitions observed following ²⁸P decay has been increased from 15 to 34. New β⁺ branches were observed to ²⁸Si levels at 7416, 9796 and 10209 keV and sharper limits were placed on unobserved gb⁺ transitions.     

Der Zerfall des122Xe (T 1/2=20,l h) und des122J (T 1/2=3,6min)

Theγ spectra emitted in the decay of¹²²Xe and¹²²I have been investigated using Ge(Li) detectors and a Ge(Li)-NaI coincidence apparatus. 14γ transitions with energies between 61.8 and 416.9 keV have been identified in the decay of¹²²Xe, 44 transitions between 564.0 and 3,291.0 keV in the decay of¹²²I. Level schemes having 7 excited levels for¹²²I and 21 excited levels for¹²²Te are proposed.     

Anomalous conversion in the decay of197mHg

The total andK-shell conversion coefficients of the 165 keV transition in the decay of^197mHg are determined from intensity balance considerations and a coincidence technique using a Ge(Li)—NaI (Tl) system respectively. The resultant values area _T =274.8±19.2 anda _K =47±12, whil the corresponding theoretical values are 344 and 77 respectively, indicating anomalous conversion. The gamma ray transition probability however, shows a hindrance of only about 6 and cannot be correlated with the present anomalous conversion data. TheK/L ratio of the 130 keV transition, determined using a summing method with a Ge(Li) detector, yielded 0.090±0.012, while the corresponding theoretical value is 0.048, indicating anomalous conversion. The corresponding gamma transition probability shows a hindrance of about 3000, in correlation with anomalous conversion.     

Search for weak transitions in the decay of125Sb and accurate gamma intensities

The weak transitions in the decay of¹²⁵Sb have been investigated through gamma ray measurements with high resolution X-ray and with large volume Ge(Li) detectors. The 172.6, 178.8 and 198.5 keV gamma rays are confirmed, while others previously reported were not. Accurate intensities were obtained for the stronger transitions. The weighted averages of these intensities which cover the range of 116 to 670 keV are useful for calibration of Ge(Li) systems.     

Decay of78Br

The decay of⁷⁸Br was investigated with a Ge(Li) spectrometer and Ge(Li)-NaI(Tl) coincidence methods. Accurate energy and intensity determinations of 14 gamma rays have been performed. A level scheme with levels at 614.0, 1,308.1, 1,498.4, 1,758.5, 1,993.7, 2,334.4, 2,538, 3,090 and 3,253 keV is deduced. Spin and parity indications for most of the observed levels are given from electron capture and positon decay considerations and gamma branches.     

The decay of208Tl. Gamma-ray measurement

The gamma rays following the decay of²⁰⁸Tl have been studied using a separated²⁰⁸Tl-source and a Ge(Li)-detector. A decay scheme is proposed, with levels in²⁰⁸Pb at 3,920, 4,126 and 4,180 keV in addition to previously well-established levels. No support was found forΒ-branching to levels above 4.2 MeV.     

The decay of Ag

The γ-radiation following the decay of ¹¹²Ag has been studied with a Ge(Li) detector. A total of 76 γ-rays was observed. The γ-γ coincidence and angular correlation relations involving the 617 keV 2⁺-0⁺ transition have been measured using Ge(Li)-NaI(Tl) and NaI(Tl)-NaI(Tl) detectors. These results have been used to confirm spins and parities of some levels of ¹¹²Cd in the proposed decay scheme. Cross sections for ¹¹²Ag production by ¹¹⁵In(n,α) and ¹¹²Cd(n, p) reactions have been measured; the ¹¹²Ag half-life has been determined as 3.14 ± 0.02 h.